need help getting the bronco running

[shawn.m]

well i brought smash9002's bronco home. Guy sold it cheap to me as it is not running very well.

he replaced MAS sensor, crank sensor, TPS, EGR purge solenoid, Intake Air Temp, cleaned IAT - I took IAT off and verified it was cleaned and worked correctly

now it runs fine when cold when it is closed loop. after it goes to open loop. it has a interment run problem. Basically bucks and dies with check engine light coming on. A couple of times it has acted like it ran out of fuel and would crank dry. After a a minute or two of cranking it catches and fires. Almost like a old school carb motor.
Sometimes it seems that as soon as you let out the clutch it kills the motor. put in the clutch and it runs fine. Let out the clutch and it starts to die.
Other thing was that it would die and lose power to the tach, then come back up to speed. Which speaks to a electrical issue

codes are 565 EGR purge solenoid, and 522 Neutral Safety switch. the neutral safety switch was hot wired so it was neutral all the time. I put it back together with crimp connectors so it works correctly. verified if it is in gear that it will not start even with clutch in.Put it in neutral with clutch down and it starts fine.

verify on the EGR purge solenoid that when 12v is applied to it - opens.

kinda stumped at this point. I fixed what the error codes point to. Only thing I can think of next is that the neutral switch and EGR solenoid are on the same tree of the wiring harness.
any ideas?

 

[kimcrwbr1]

go through and check and clean all your grounds sounds like a ground issue to me being intermittent

 

[kimcrwbr1]

are you sure on the egr solenoid I cannot find it on the schematic but the neutral safety switch is only for starting in park neutral A/T neutral M/T are you thinking vapor cannister solenoid it is tied with the converter clutch or shift and purge solenoid

 

[country0001]

go through and check and clean all your grounds sounds like a ground issue to me being intermittent

Ditto on that, bout a year ago, I could start mine from the outside of truck. As soon as I sat in the truck it would die. Turned out to be the ground cable from the engine to the frame. Baffled me for a long time.

 

[master hec0]

mine had the exact same symptoms did all of that and it turned out to be a bad o2 sensor.
because in closed loop it uses factory preset info to run the engine and once it goes open the sensor is telling it wrong info causing it to run like crap and stall. i would replace it.

 

[shawn.m]

are you sure on the egr solenoid I cannot find it on the schematic but the neutral safety switch is only for starting in park neutral A/T neutral M/T are you thinking vapor cannister solenoid it is tied with the converter clutch or shift and purge solenoid

the motor is a 93 and does not have a EGR valve. the egr purge solenoid seems to refer to the evap cannister in the front next to the radiator.

mine had the exact same symptoms did all of that and it turned out to be a bad o2 sensor.

a bad O2 sensor should throw a code during KOEO test. O2 sensor is easy to replace and will go on the list to replace.

ground issue - the wires seem to be run correctly at the motor. someone else mentioned that.
I know the battery to motor wire works. need to check all the other ones.

 

[kimcrwbr1]

yea battery to chassis and all other grounds there should be about 5 for the computer you say the engine is a 93 and the bottom of the post says 89 B2 4.0 confised on what your doing here

 

[shawn.m]

body is a 89 bronco 2 with a 93 4.0 engine, wiring harness, exploder dash and wiring harness. - see smash9002 build for the build details of suspension. conversion was done in 2002 and BAR referee decal on door. It ran fine when he sold it 2 months ago.

bought some 6 gauge wire with ring connectors. Going to bolt a couple in at strategic places and see what happens.

 

[shawn.m]

ran 6 gauge wire from battery to ground right below computer, ground wire from battery to alternator, cleaned all connections for negative and positive and put ring terminals on open wires to negative terminal.
idle was really high and not coming done that fast. Unplugged the IAC and it ran better . Idled nice and low.

runs better but still getting the kill situation where it just dies. hit the clutch and let it idle and it almost cleans itself out. idled around my property for 30 minutes and it ran better . Only 1 or 2 situations where it died. It is almost acting like bad gas.

 

[shawn.m]

bought a ford factory 1992 powertrain/emmisions book at a garage sale today for $2! SCORE

 

[adsm08]

If it wasn't for the codes I'd say O2.

The starting problem sounds like its in the Neutral Sense circuit. Start with the switch and go from there.

EGR codes might be the flow sensor, might be a leaky valve.

 

[retep88]

I would replace the O2. My guess is that the O2 sensor is producing a false signal that doesn't trip a code. Computers aren't perfect, and neither are sensors. They can fail in ways that won't trip a code. that is why you have to be smarter then what you are working on Taking a volt meter to the O2 sensor will tell you for sure. Wait until it gets warm and goes into closed loop. Watch the voltage when you give it throttle or load, if the voltage doesn't move, or spike or anything you might have a problem. Of course cleaning grounds and such never hurt anything either.

edit: another thought. check the throttle position sensor. it should read around 0 for closed throttle and somewhere between 3-5 for open. The more important thing is that it's a smooth transition as you open the throttle. Or the map sensor in a similar fashion

 

[IlovemybroncII]

ok this is just another hint may or may not be problem but on my 05 f250 i would get high rpms and no power run like crap throw all kinds of codes and what it end up being was the screen on the fuel pump was so cloged up with crap would get fuel then it would not I removed screen and that was a big mistake truck would not run at all put new way too damn costly fuel pump in run like new hope this helps

 

[shawn.m]

remember this is a 93 4.0 with MAS air and dual O2 sensors. I have a Air/Fuel O2 meter sitting on my shelf that I think I might throw on just for fun.

TPS voltage is .95 at close with a smooth trip to 4.5 -TPS and MAS sensor were both replaced.
I am thinking of dropping the tank and cleaning it just to make sure that the fuel pump screen is not plugged or blocked. Has new fuel filter also.
bought a fuel pressure gauge today so I can do the KOEO fuel pressure test and the running one.

 

[shawn.m]

ran new vacuum line from EGR purge solenoid to EVAP cannister.

Opened my new Fuel Pressure Gauge. Fuel pressure KOEO fuel pressure was 38psi, steady state 32PSI and goes up to 39PSI as soon as you hit the gas. So that is not the issue. Vacuum steady state is 18 in.

Big thing I noticed after doing all the Grounds correctly and redoing the positive cable was that the charge voltage shot up to 16volts. Drove it around the farm again for a while charging the battery. Now the hesitation dieing is gone!

Idle is now 1000 rpm and it runs great! Lots of power down to 1500rpm and up to 5500. Had all 4 wheels spinning in a mud puddle

SO STOKED! :

So final analysis may be that battery voltage was not where it needed to be and then the computer needed to relearn everything after proper grounding was done.

next up is smog test and title transfer